Flow meters are important in many applications, such as oil and gas pipeline flow monitoring. It is important for economic and safety reasons to have accurate flow measurements. Differential pressure flow meters are commonly used. A differential flow meter is based on Bernoulli's theorem and the conservation of mass of a fluid flow between two points in a flow, and can provide a flow rate reading (in mass or volume) expressed as a function of measured differential pressure and the fluid density.
A differential pressure meter measures a pressure drop produced using a differential pressure producer, such as an obstruction body or constriction introduced into the fluid flow. The differential pressure meter provides a flow rate calculated using known flow rate equations. For its part, the differential pressure producer may be either a constriction formed in the conduit or an obstruction body inserted into the conduit. Examples of differential pressure meters include the McCrometer WAFER CONE flow meter and the McCrometer V CONE flow meter, which operate using obstructions. V CONE and WAFER CONE are registered trademarks of McCrometer in the United States and other countries.
In order to measure pressure differential within a conduit, pressure tappings or ports are configured both upstream from the obstruction and at or in the vicinity of the obstruction in order to produce high and low pressure readings. The differential in pressure between the two pressure points is monitored and used for flow rate calculations. The standard DP meter flow equation is well known.